What determines birth weight?
Birth weight is determined by multiple interacting factors. These include genetics; how many weeks your baby has been gestating; the quality and quantity of mum’s food during gestation; any disease and illness; smoking, alcohol and drug consumption; the sex of the baby; and whether the baby is part of a multiple pregnancy (twins, triplets etc.).
What is an average birth weight?
The average birth weight of babies born between 37 and 42 weeks (full-term) is 3.4kg for females and 3.5kg for males. Most babies fall somewhere between 2.5kg and 4kg.
Why is it important to know?
A low birth weight can be a sign or symptom of other health complications. It’s also important to know and track a baby’s weight because most healthy babies experience reasonably consistent weight gains over the first days, weeks and months of their lives.
Health professionals will track a baby’s weight gain against a chart of weight-for-age. These charts show the normal range and progress of weight gain and be used an indicator for whether a baby is experiencing problems putting on weight. This can be a sign of a health problems or an issue with feeding, with weight loss a particular cause for concern.
So while your baby’s starting weight might not be important by itself, it provides a useful figure for charting their health and progress over the weeks and months to come.